The present invention relates to an airbag device for a front passenger seat installed in an automobile. More particularly, the present invention relates to an airbag device in which a door of the airbag device lifts and opens toward a vehicle cabin when an airbag is deployed.
An airbag device for a front passenger seat installed in an automobile comprises an airbag in a folded state, a retainer for retaining the airbag, an inflator (gas generator) for inflating the airbag, and a lid or a door portion of an instrument panel disposed in front of the retainer. When the inflator generates gas, the airbag starts to be inflated and the lid or the door portion of the instrument panel is torn along a tear line and pressed to open by the airbag. Accordingly, the airbag is deployed into a vehicle cabin to protect an occupant.
Japanese Patent Publication (Kokai) No. 2003-137054 has disclosed an airbag device in which a door portion of an instrument panel is structured to lift and open toward an inside of a vehicle cabin when the airbag is inflated, so that the door portion of the instrument panel opens smoothly.
FIG. 4 is a sectional view of the airbag device disclosed in Japanese Patent Publication (Kokai) No. 2003-137054. FIG. 5 is a sectional view thereof in use, and FIG. 6 is a perspective view of a door frame. As shown in FIG. 4, an airbag 52 (FIG. 5) is folded and accommodated in a retainer 50 having a container-like shape with an open top. The airbag 52 is inflatable by an inflator 54. An upper side of the retainer 50 is covered with an instrument panel 60. The instrument panel 60 is provided with tear lines 62a and 62b formed of grooves. The tear line 62b extends along an upper periphery of the retainer 50. A portion surrounded by the tear line 62b becomes a door portion 64. The tear line 62a extends laterally at the middle of the door portion 64.
A door frame 70 is disposed on a backside of the instrument panel 60, and comprises a door frame movable member 72 and a door frame fixed member 74. The door frame fixed member 74 is formed of a rectangular frame, and the door frame movable member 72 is slidably fitted into the door frame fixed member 74. The door frame movable member 72 has a backing plate 72a attached to the door portion 64 of the instrument panel 60 and leg plates 72b as leg portions extending downwardly from both sides of the backing plate 72a. Hook holes 72c are formed in the leg plates 72b. The backing plate 72a is provided with a tear line 72d at a position aligning with the tear line 62a. Hinge chamfers 72e formed of grooves extend along corners between the backing plate 72a and the leg plates 72b, respectively. The backing plate 72a is bonded to a backside of the door portion 64 of the instrument panel 60 with vibration welding.
The door frame fixed member 74 comprises a leg frame 74a as a rectangular frame-like leg portion extending around an outer periphery of the retainer 50 and a flange portion 74b projecting outwardly from an upper edge of the leg frame 74a. The flange portion 74b is bonded to a peripheral portion of the door portion 64 of the instrument panel 60 with vibration welding. Hook holes 74c are formed in the leg frame 74a. Hooks 78 with a J shape are fixed to the retainer 50 and inserted into the hook holes 72c and 74c. 
When the inflator 54 starts to eject gas, the airbag 52 is inflated and pushes the door frame movable member 72 to move upwardly (lift), as shown in FIG. 5. The instrument panel 60 is torn along the tear line 62b, so that the door portion 64 is separated from the instrument panel 60 around the door portion 64. The door portion 64 further moves upwardly together with the door frame movable member 72, and is further pressed by the airbag 52, so that the backing plate 72a and the door portion 64 are torn along the tear line 72d and the tear line 62a, respectively. As a result, the door portion 64 is divided into two pieces in the rightward and leftward directions so as to open like a door as shown in FIG. 5, thereby deploying the airbag 52 into the vehicle cabin.
The door portion 64 lifts and is separated from the instrument panel 60 around the door portion 64, so that the door portion 64 smoothly opens without receiving a reaction force from the instrument panel 60 around the door portion 64.
In the airbag device disclosed in Japanese Patent Publication (Kokai) No. 2003-137054, as shown in FIGS. 4 to 6, the leg frame 74a of the door frame fixed member 74 has a large height, thereby increasing a weight of the door frame fixed member 74 and material cost for production.
In view of the problem described above, an object of the present invention is to provide an airbag device having a door frame formed of a door frame fixing member and a door frame movable member, in which the door portion is opened when the door frame movable member lifts. In the airbag device of the present invention, it is possible to reduce a weight and cost of the door frame.
Further objects and advantages of the invention will be apparent from the following description of the invention.